This invention relates to the low cost detection of lightning. Most lightning detectors detect the electromagnetic field of the return stroke of a cloud to ground strike and indicate the approximate distance to the strike. Previous developments in the field of lightning detection include ranging systems that display the distance to lighting strikes (U.S. Pat. No. 3,715,660 Ruhnke) and devices that use CRTs to display the azimuth and distance from the user (U.S. Pat. No. 4,023,408, Ryan et al).
The use of 2 perpendicular, horizontal coils for detecting the electromagnetic signal of lightning strikes is common practice. This allows one antenna to detect north-south (NS) strikes and the other to detect east west (EW) strikes. To determine the strength of a strike that is not perfectly perpendicular to the coils requires a summing operation with both components. This summing operation must happen very quickly so that the return stroke leading edge of lightning strike can be recognized and to trigger subsequent data acquisition. Some practical problems arise when aggregating the two channels. To create a low cost system, a processor without advanced hardware floating point math capability must be employed. This results in the use of floating point libraries when summing operations, such as the square root of the sum of the squares require a much longer time periods than required by a real time lighting detection system. Additionally, the power consumption of more complex processors capable of performing the summing operation would lessen the battery life of a portable, low cost product.